Control device of an operating element in a motor vehicle

ABSTRACT

A receiver belongs to a control device of an operating element in a motor vehicle, which receiver is a component part of the operating element and into which signals are able to be inputted by a person. In order to be able to establish with great reliability a threshold for the decision ‘signal valid/signal invalid”, it is proposed defined in the invention that the receiver of the operating element has a first coupling-in element and a second coupling-in element, which are arranged at a defined distance from one another on an evaluation axis.

The invention relates to a control device of an operating element in amotor vehicle, with a receiver that belongs to the operating element andinto which signals are able to be inputted by a person.

This control device is able to be configured by means of near fieldcommunication so that a person identification is possible, wherein inparticular the differentiation can implemented between passenger anddriver or respectively the driver recognition generally.

It is to be ensured hereby that particular actions or respectivelyinterventions with equipment, e.g. the selecting of a drive position inan automatic gearbox, can only be carried out by the driver.

A corresponding control device is known from DE 43 01 160 C2, in whichthe driver's seat and the passenger's seat are marked by a specificsignal. In this known case, only the frequency of the signal isdifferent and is allocated explicitly to the driver's seat orrespectively to the passenger's seat. The marking signal is coupled intothe person situated on the respective seat via the seat frame or asuitable coupling surface. The respective actuating- or respectivelyoperating element is additionally configured as a signal receiver. Inthe case of an actuation of the respective actuating- or respectivelyoperating element, the body of the respective person forms a signal pathfor the marking signal. With the aid of the specific signal frequency,the operating element recognizes the person who is acting and cantrigger or prevent corresponding actions.

Both the coupling in of the marking signal and also its transmission issubject to great fluctuations. The signal level at the receiving elementon the actuating side or respectively operating element side can varycompletely by a factor of 200. This is due, for example, to whatclothing a person is wearing, whether possibly a seat cushion is beingused on the vehicle seat or whether the person who is acting—for examplein winter—is wearing gloves.

In the case of the known control device, a decision is made on the basisof the signal strength detected in the receiving element whether anactuation is present by the respective person. With the fluctuations ofthe signal strength described above, such a solution is notsatisfactory, because it is only possible with a comparatively smalldegree of accuracy to establish a threshold for the —signal valid/signalinvalid” decision.

Proceeding from the prior art described above, the invention is based onthe problem of further developing the control device, described in theintroduction, of an operating element in a motor vehicle such that witha much greater reliability than in the prior art and with acomparatively small technical/structural expenditure a distinct andexact threshold can be established for the “signal valid./signalinvalid” decision.

This problem is solved according to the invention in that the receiverof the operating element has a first and a second coupling-in elementthat are arranged at a defined distance from one another on anevaluation axis.

It is known from physics that an electrical or magnetic field drops offwith a decreasing gradient at an increasing distance from the fieldsource. In the case of the invention, through the evaluation of thegradient of the electrical or respectively magnetic signal field,wherein the magnetic field is linked with the electrical field accordingto Maxwell's equations, the distance between the signal source and theoperating element is able to be determined reliably.

For this, advantageously the quotient of the signal strength detected atthe first coupling-in element of the receiver and the signal strengthdetected at the second coupling-in element of the receiver is used asthe basis for the measuring or respectively for the determining of thedistance between the signal source and the operating element.

As the quotient of the two signal strengths is used as a benchmark forthe distance, the distance is only dependent on the ratio of the signalstrength of the two signals and no longer on the absolute signalstrength.

A specific signal for the respective person can be transmitted forexample by means of a transmitter which is carried by the respectiveperson.

If, alternatively, an electrical field coupled into the respectiveperson functions as a signal, variable factors do not play a part in thecoupling-in of the signal into the human body. The same applies for thetransmission behavior of the human body. Also, the use of gloves has noinfluence on the determined distance.

Advantageously, the first and the second coupling-in element of thereceiver are constructed as field sensors,

The field sensors on the receiver side can be constructed expediently asmagnetic field sensors, by means of which the specific signaltransmitted from the transmitter for the respective person orrespectively a magnetic field corresponding to the electrical fieldwhich is coupled into the person is able to be evaluated. According tothe invention, it is therefore possible to couple an electrical fieldinto the body as a signal, wherein, however, the coupling elements onthe receiver side are constructed as magnetic field sensors, by means ofwhich the magnetic field corresponding to the electrical field isevaluated.

Basically, it is possible to configure the field sensors on the receiverside as field plates.

According to an advantageous embodiment, the field sensors on thereceiver side are constructed as field coils. The field coils can beevaluated free of potential and have a comparatively low impedance thatlies distinctly below the impedance of field plates. The sensitivity ofthe field coils can be influenced with an extremely low expenditure bythe number of windings which are applied.

According to a further advantageous embodiment, the sensitivity of thefield coils can be drastically increased if a capacitor is associatedwith each field coil, which capacitor forms a resonant circuit with itthat is coordinated with the frequency of the electrical fieldfunctioning as a signal.

According to a further advantageous embodiment of the invention, thecontrol device has a coupling member, by means of which the signal isable to be coupled into the body of the person and which can be arrangedfor example on a vehicle seat or on a steering wheel.

A differentiation of different persons situated in the motor vehicle canbe achieved by means which are minimally elaborate from atechnical/structural point of view, when the specification of thesignals associated with different persons situated in the motor vehicleor respectively with different vehicle seats is realized by means of apresettable chronological sequence of the respective signals. Thus, forexample, firstly the signal associated with the driver's seat, then witha chronological interval the signal associated with the passenger'sseat, then with the same chronological interval the signal associatedwith the right rear seat, then with the same chronological interval thesignal associated with the middle rear seat, and then with the samechronological interval the signal associated with the left rear seat aretransmitted, before then—with an e.g. considerably greater chronologicalinterval—again the signal associated with the driver's seat istransmitted. Further differences between the signals associated withdifferent persons or respectively vehicle seats are not then necessary.

According to an advantageous further development of the control deviceaccording to the invention, the first one coupling element and thesecond one coupling element can be configured so that the signalstrengths detected by them at a presettable distance, e.g. at anoperating distance between them and the signal source, are of equalextent. With correspondingly configured coupling-in elements, it is thenparticularly simple with regard to circuitry to configure adistance-dependent switch. The forming of the quotient of the signalstrengths detected by the receiver can be dispensed with, because itonly still has to be decided in the control device whether the quotientlies above or below 1 or respectively which of the two coupled-insignals is greater or respectively stronger. For this, merely a simplecomparator is necessary. If the distance of the signal source is greaterthan the presettable distance or respectively the operating distance,then the signal of the coupling-in element more remote from the signalsource is greater than that of the coupling element nearer to the signalsource. When the distance between the signal source and the coupling-inelements corresponds exactly to the presettable distance or respectivelythe operating distance, the signal strengths of the two coupling-inelements are of exactly equal extent. When the distance between thesignal source and the two coupling-in elements is smaller than thepresettable distance or respectively the operating distance, then thesignal strength of the coupling-in element closer to the signal sourceis greater than the signal strength of the coupling-in element moreremote from the signal source.

The corresponding configuration of the coupling-in elements can bebrought about in a minimally elaborate manner from atechnical/structural point of view if the field plate or respectivelythe field coil of the coupling-in element further remote from the signalsource is constructed so as to be correspondingly greater with regard toarea or respectively with more bindings than the field plate orrespectively the field coil of the coupling-in element closer to thesignal source.

The configuration of the coupling-in elements explained above can beachieved in an even simpler manner from a technical/structural point ofview if the coupling-in element closer to the signal source has acorrespondingly configured downstream signal attenuator_(—)

The invention is explained in further detail below with the aid of anembodiment, with reference to the drawings, the single FIGURE of whichshows a schematic diagram of an embodiment of a control device of anoperating element according to the invention, in a motor vehicle.

A person 1 has sat down on a vehicle seat 2. Inside a motor vehicle, notfurther illustrated, provided with the vehicle seat 2, an operatingelement 3 is provided that serves for the putting into operation,actuation, control etc. of downstream equipment. For example, a gearshift knob of a selector lever or suchlike can be provided as operatingelement 3.

The operating element 3 has a receiver 4. By means of the receiver 4,the person 1 situated on the vehicle seat 2 can input operating signalsinto the operating element 3.

In the illustrated example embodiment of the control device according tothe invention, a coupling member 5 is provided in or respectively on thevehicle seat 2, by means of which a specific signal is able to beinputted into the body of the person 1, wherein this is expediently anelectrical signal here in the case of the control device according tothe invention. The body of the person 1 becomes, as it were, a signalsource.

In order to determine a distance E between a hand of the person 1,forming a part of the person 1 or respectively of the signal source onthe one hand, and on the other hand the operating element 3 in areliable manner and independently of the level height of the signalwhich is coupled into the person 1, the receiver 4 of the operatingelement 3 has a first coupling-in element 6 and a second coupling-inelement 7.

The two coupling-in elements 6, 7 are arranged on an evaluation axis 8.They have a predetermined defined distance A with respect to one anotheron this evaluation axis 8.

At his point, it is to be pointed out that the electrical signal whichis inputted into the person 1 by means of the coupling member 5 isspecific and characteristic for the vehicle seat 2. In an evaluationunit 9 of the receiver 4, to which both the first coupling-in element 6and also the second coupling-in element 7 of the receiver 4 areconnected, an association can be brought about of the respectivelyreceived signal to the respective vehicle seats. Through the near fieldcommunication which is configured in such a way, the control device ofthe operating element 3, described above, is enabled to establish, on anactuation of the receiver 3, which of the persons 1 situated in thevehicle is operating the operating element 3. In particular, adifferentiation can be undertaken here between the vehicle driver andother persons situated in the vehicle. Hereby, it can be ensured thatparticular operating procedures can be carried out exclusively by themotor vehicle driver and other operating procedures can in fact not becarried out by the motor vehicle driver.

In the illustrated example embodiment of the control device, thequotient of the signal strength detected at the first coupling-inelement 6 of the receiver 4 and of signal strength detected at thesecond coupling-in element 7 of the receiver 4 is formed in theevaluation unit 9 of the receiver 4.

In the evaluation unit 9, the gradient is evaluated of the electrical orrespectively magnetic signal field going back to the signal which iscoupled in to the body of the person 1, wherein the magnetic field islinked with the electrical field in accordance with the Maxwell'sequations.

Accordingly, in the case of the illustrated embodiment an electricalfield is coupled into the body of the person 1 as a signal, wherein thefirst coupling-in element 6 and the second coupling-in element 7 of thereceiver 4 are configured as magnetic field sensors or respectivelyfield coils 6, 7 for the evaluation of the magnetic field.

Instead of field coils 6, 7, field plates can also be provided. Theconfiguration of the coupling-in elements 6, 7 as field coils 6, 7 hasthe result, however, that a potential-free evaluation of the signalsdetected by the field coils 6, 7 is possible. Furthermore, field coils6, 7 have a considerably lower impedance than field plates that are ableto be used alternatively.

Depending on the requirement profile for the receiver 4 of the operatingelement 3, coupling-in elements 6, 7, constructed as field coils, can beprovided with a corresponding number of the applied windings.

To increase the sensitivity, it is possible that a coupling-in element6, 7, constructed as a field coil, forms a resonant circuit with anadditionally provided capacitor, which resonant circuit is coordinatedwith the frequency of the electrical signal which is inputted into thebody of the person 1.

As an electrical or magnetic field drops off with a decreasing gradientat an increasing distance from the field- or respectively signal source,the distance E between the operating element 3 and the signal source,for example the hand of the person 1, can be exactly determined in theevaluation unit 9 of the receiver 4. This exact determining isindependent of the signal level, received in the receiver 4 of theoperating element 3, of the electrical signal which is inputted into theperson 1.

In the arrangement of the two field coils 6, 7 one behind the other onthe evaluation axis 8, indicated in principle in the FIGURE, it isprevented that the first field coil 6 shields the magnetic orrespectively electrical field with respect to the second field coil 7.

The evaluation in the evaluation unit 9 of the receiver 4 takes place bysimple measuring and detecting of the signal strength at the twocoupling-in elements 6, 7 or respectively field coils 6, 7. The quotientof the two detected signal strengths is used as benchmark for theevaluation. Accordingly, the evaluation or respectively the determiningof the distance E is dependent exclusively on the ratio of the signalstrength of the two signals detected at the field coils or respectivelycoupling-in elements 6, 7, and no longer on the absolute signalstrength. It is essential that the distance A between the twocoupling-in elements 6, 7 is predetermined and defined.

Any variable coupling factors which occur on the input of the electricalsignal into the body of the person 1 by means of the coupling member 5do not play any part with regard to the evaluation in the receiver 4 ofthe operating element 3. Also, the transmission behavior of human bodyof the person 1 or, for example, the use of gloves, influencesexclusively the absolute signal strength, but not the quotient formed inthe evaluation unit 9 of the receiver 4.

The smaller the distance E between the signal- or respectively fieldsource and the operating element 3, the greater the quotient, formedfrom the two signal strengths detected by means of the coupling-inelements 6, 7, which quotient serves as the basis for the detection orrespectively calculation of the distance E.

In the example embodiment described above, the coupling member 5, bymeans of which the electrical signal is inputted into the body of theperson 1, is provided on the vehicle seat 2. Of course, it is alsopossible to provide a coupling member on the steering wheel, forexample, instead of on the vehicle seat.

In the embodiments described above, the coupling-in elements 6, 7 thatare arranged at a distance from one another on the evaluation axis, areconstructed identically. This has the disadvantage technically that thecoupling-in element 7 which is further remote from the signal source,for example from the hand of the person 1, receives a signal with adistinctly smaller signal strength. In the subsequent signal processingor respectively evaluation unit 9 therefore in certain circumstances ahigher signal enhancement is necessary for this coupling-in element 7.However, it is technically advantageous if an identical signal path canbe used for both coupling-in elements 6, 7.

For this, according to a further embodiment of the control deviceaccording to the invention, the coupling-in elements 6, 7 are configuredso that with a defined and presettable distance or respectively with theoperating distance between the signal source and the two coupling-inelements 6, 7, the signal which is coupled into the latter is of equalextent. This can be realized with coupling-in elements 6, 7 equippedwith field plates, for example in that the field plate of thecoupling-in element 7 which is more remote from the signal source isconfigured accordingly to be larger with regard to area than the fieldplate of the coupling-in element 6 which is nearer to the signal source_In so far as the coupling-in elements 6, 7 are equipped with fieldcoils, the field coil of the coupling-in element 7 which is more remotefrom the signal source can have more bindings accordingly than the fieldcoil of the coupling-in element 6 which is nearer to the signal source.

Alternatively, it is possible that the coupling-in element 6 which isnearer to the signal source is equipped with a correspondinglyconfigured downstream signal attenuator.

In so far as the coupling-in elements 6, 7 are configured so that thesignal strength which is passed on from them to the evaluation unit,with the presettable distance or respectively operating distance betweenthe coupling-in elements 6, 7 and the signal source, are of equalextent, it is particularly simple with regard to circuitry to configurea switch which is dependent on distance. The forming of the quotientbetween the two signal strengths is superfluous, because it only stillhas to be differentiated whether the quotient between the signalstrengths lies above or below 1 or is equal to 1, which corresponds tothe decision as to which of the signal strengths is greater. A simplecomparator is sufficient for this.

If the distance E between the signal source or respectively the person 1and the operating element 3 is greater than the presettable distance orrespectively the operating distance, then the signal strength of thecoupling-in element 7 which is more remote from the signal source orrespectively the person 1 is greater than the signal strength of thecoupling-in element 6 nearer to the signal source or respectively theperson.

In so far as this distance E corresponds to the presettable distance orrespectively the operating distance, the two signal strengths are ofequal extent.

If the distance E between the signal source or respectively the person 1and the receiver 4 is smaller than the presettable distance orrespectively the operating distance, then the signal strength of thecoupling-in element 6 nearer to the signal source or respectively theperson 1 is greater than that of the coupling-in element 7 which isfurther remote from the signal source or respectively the person 1.

1. A control device of an operating element in a motor vehicle, with areceiver that belongs to the operating element and into which signalsare able to be inputted by a person, wherein the receiver of theoperating element has a first coupling-in element and a secondcoupling-in element that are arranged at a defined distance from oneanother on an evaluation axis.
 2. The control device defined in claim 1,wherein the quotient of the signal strength detected at the firstcoupling-in element of the receiver and the signal strength detected atthe second coupling-in element of the receiver is the basis for themeasuring or respectively determining of the distance between the signalsource and the operating element.
 3. The control device defined in claim1, further comprising: a transmitter able to be carried by the personand by means of which signal which is specific for the person is able tobe transmitted.
 4. The control device defined in claim 1, wherein anelectrical field, functioning as a signal, is able to be coupled intothe person.
 5. The control device defined in claim 1, wherein the firstcoupling-in element and the second coupling-in element of the receiverare constructed as field sensors.
 6. The control device defined in claim5, wherein the field sensors on the receiver side are constructed asmagnetic field sensors, by means of which a magnetic field correspondingto the specific signal transmitted by the transmitter or respectively tothe electrical field coupled into the person is able to be evaluated. 7.The control device defined in claim 5, wherein the field sensors on thereceiver side are constructed as field plates.
 8. The control devicedefined in claim 5, wherein the field sensors on the receiver side areconstructed as field coils.
 9. The control device defined in claim 8,wherein a capacitor is associated with each field coil, which capacitorforms with it a resonant circuit that is coordinated with the frequencyof the electrical field functioning as a signal.
 10. The control devicedefined in claim 4, further comprising: a coupling member that cancouple the signal into the body of the person.
 11. The control devicedefined in claim 10, wherein the coupling member is arranged on avehicle seat.
 12. The control device defined in claim 10, wherein thecoupling member is arranged on a steering wheel.
 13. The control devicedefined in claim 1, wherein the specification of the signals associatedwith different persons situated in the motor vehicle or respectivelywith different vehicle seats is realized by means of a presettablechronological sequence of the respective signals.
 14. The control devicedefined in claim 1, wherein the first coupling-in element and the secondcoupling-in element are configured so that the signal strengths whichare detected by them, with a presettable distance, e.g. with anoperating distance, between them and signal source, are of equal extent.15. The control device defined in claim 14, wherein the field plate orrespectively the field coil of the coupling-in element which is furtherremote form the signal source is constructed correspondingly greaterwith regard to area or respectively with more bindings than the fieldplate or respectively field coil of the coupling-in element nearer tothe signal source.
 16. The control device defined in claim 14, whereinthe coupling-in element nearer to the signal source has acorrespondingly configured signal attenuator.